Method for the direct reduction of iron using gas from coal

Abstract

A method for direct reduction of iron in a shaft reduction furnace. Spent gas from the furnace is upgraded in reductant by removal of CO2 and water to form an upgraded gas. A fossil fuel is gasified to produce a hot gas which is tempered with a first stream of upgraded gas. The mixture is desulfurized by reaction with lime to produce hot desulfurized gas. A second stream of upgraded gas is heated and mixed with the hot desulfurized gas to produce hot reducing gas.

What is claimed is: 
     
       1. In a method for reducing iron oxide in a direct reduction furnace wherein hot reducing gas is introduced to said furnace to reduce the iron oxide therein to a metallized iron product and to form a CO 2  containing spent reducing gas, the improvement comprising: a. removing a substantial portion of the CO 2  from said spent reducing gas to form a reductant-rich gas;   b. gasifying fossil fuel to form a hot gasifier gas;   c. tempering said hot gasifier gas with a first stream of said reductant-rich gas to form a hot gas mixture;   d. reacting said hot gas mixture with a sulfur acceptor to form a hot desulfurized gas;   e. heating a second stream of said reductant-rich gas; and   f. mixing said heated second stream of reductant-rich gas with hot desulfurized gas to form a reducing gas having a quality of at least about 8 and a temperature of from about 760° to about 900° C. for introduction to said furnace.   
     
     
       2. A method according to claim 1 wherein said sulfur acceptor is lime. 
     
     
       3. A method according to claim 1 wherein said gasifier gas has a quality of at least about 6. 
     
     
       4. A method according to claim 1 wherein a portion of the CO 2  containing spent reducing gas is used as fuel to heat said second stream of reductant-rich gas. 
     
     
       5. A method according to claim 1 wherein said fossil fuel is selected from the group consisting of coal, lignite and char. 
     
     
       6. A method according to claim 1 further comprising mixing a third stream of unheated reductant-rich gas with said desulfurized gas to control the reducing gas temperature.